Bulletin of the Museum of Comparative Zoology, 
AT HARVARD COLLEGE. 


Vou. VE Nos-8, 9. 


No. 8. 
LETTER No. 4. 


To 0. P. PATTERSON, Supt. U.S. Coast Survey, from ALEXANDER AGASSIZ, 


ON THE 


DREDGING OPERATIONS OF THE U.S. COAST SURVEY Sr, ° BLAKE,” 


i: DURING JUNE AND JULY, 1880. 


No: 9. 
a DESCRIPTION OF GRAVITATING TRAP, sy Lieut.-CoMMANDER 
ee BS C. D. Sicsper, U.S.N. 
7 


CAMBRIDGE: 
PRINTED FOR THE MUSEUM 


SEPTEMBER, 1880. 


- 


Museum of Comparative Zodlogy, Cambridge, Mass. 


Wirth the compliments of 


ALEXANDER AGASSIZ. 


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No. 8.— (LeTTER No.4.) Zo Caruite P. Patterson, Superin- 
tendent United States Coast and Ceodetic Survey, Washington, 
D. C., from ALEXANDER AGASSIZ, on the Dredging Operations 
carried on during part of June and July, 1880, by the United 
States Coast Survey Steamer “ Blake,’ Commander J. R. BARTLETT, 
U.S. LN. 


I so1nep the “Blake,” at Newport, late in June. According to your 
instructions, we proceeded to the northeastern edge of George’s Shoal, 
where we ran our first line of dredgings from the 100-fathom line to a 
depth of nearly 1250 fathoms. Our second line was run to the south- 
east, off Montauk Point. This was interrupted’ by bad weather. We 
were compelled to put into Newport, and completed the line on our 
return from the South. This line extended to nearly 1400 fathoms. 

On leaving Newport for the second time we steamed directly for 
Charleston, S. C. A line of dredgings was run from the 100-fathom 
line normal to the coast directly across the Gulf Stream to a distance of 
about 120 miles to the eastward of Charleston. Finding that our depth 
did not increase at that distance, — our greatest depth not being much 
more than 350 fathoms, —Commander Bartlett thought it prudent to 
return towards shore, to the so-called axis of the Gulf Stream, and to 
run a line in a northeastern direction parallel to the coast in the trough 
of the Gulf Stream. To our great astonishment the depth did not in- 
crease. We carried from 250 to less than 300 fathoms until we nearly 
reached the latitude of Cape Hatteras, when in a short distance there 
was a very rapid drop from 352 fathoms to 1,386 fathoms. A fifth line 
was run normal to this northern slope of the Gulf Stream plateau, to a 
depth of 1,632 fathoms. A sixth line was run to the northward of Cape 
Hatteras, to a depth of 1,047 fathoms. A seventh line was run east off 
Cape May, from the 100-fathom line to nearly 1200 fathoms. 

We were greatly disappointed in the richness of the fauna on the 
lines off Charleston and in the Gulf Stream, owing partly to the very 
gradual slope of the continent towards deep water, and the strong cur- 
rent of the Gulf Stream, which sweeps everything off the bottom along 
its course. There is but little food for the deep-water animals, and it 


was only along the edges of the Gulf Stream where mud and silt accu- 
VOL. VI. — No. 8. 


148 BULLETIN OF THE 


mulated that we made satisfactory hauls on our Southern lines. What 
was obtained seemed to be a scanty northern extension of the fauna of 
the Caribbean Sea and of the Gulf of Mexico between the 100 and 350 
fathom lines. It was not until we trawled on the steep slope of the 
Gulf Stream plateau south of Cape Hatteras, where the bottom was fine 
mud and Globigerina ooze, that we made a rich harvest again, in striking 
contrast to the poor hauls along the well-swept rocky or hard bottom of 
the Gulf Stream to the southward. Along the western edge of the Gulf 
Stream we came upon several patches of the modern green-sand forma- 
tion, where the bottom was entirely composed of perfectly clean dead 
Globigerine. Although Pteropods were very common at the surface all 
the way from Charleston to Cape Hatteras, they were only rarely brought 
up dead from the bottom ; but when the steep slope south of Hatteras 
was reached they again assumed a prominent part in the composition of 
the bottom mud. 

While running the line parallel to the coast from off Charleston to 
Cape Hatteras, we came twice upon localities where the sounding cup 
brought up nothing but clean Globigerinze, the bottom consisting en- 
tirely of the modern green-sand to which Bailey and Pourtales had 
already called attention as forming off shore on the Atlantic coast of the 
United States. The rapid changes in the character of the mud, as we 
increase both our distance from shore and the depth, are well shown in 
the nature of the bottom of the different depths along the short, steep 
line forming the northern slope of the Gulf Stream plateau traced by the 
“Blake” from Charleston to south of Cape Hatteras. We very rapidly 
pass from the comparatively coarse mud to fine and finer ooze, which 
becomes an impalpable silt in the deeper water beyond 1,000 or 2,000 
fathoms, assuming at the same time gradually a lighter color. 

Among the Tunicates I may mention two new species of Salpz, one 
of which is interesting, its chain occupying an intermediate position 
between that of Salpa pinnata and the ordinary Salpa chain of 8. zo- 
naria or S. Cabotti of our coast. The solitary individuals are gigantic 
specimens, measuring no less than twelve inches in length. This solitary 
form is: closely allied to S. maxima, but differs from it in the number 
and arrangement of the muscular bands. The chains grow to a great 
length, some of them measuring more than ten feet in length and as 
much as nine inches in breadth. The zodids are arranged as in S. pin- 
nata, side by side in a single row, extending vertically across the whole 
width of the chain, and forming a thin ribbon, which when floating is 
usually slightly coiled like a tape. The zodids of the chain resemble 


MUSEUM OF COMPARATIVE ZOOLOGY. 149 


S. Africana. This species was found at sea from Cape Hatteras as far 
north as the eastern extremity of George’s Shoal. 

Among the Acalephs, the most interesting form was a species of Do- 
decabostricha, Br., the largest specimen measuring no less than nine 
inches in height. Several specimens of a dark violet (claret-color) were 
brought up in the trawl, and it is very probable from the systematic aftin- 
ities of this Medusa that, like its allies, the Rhizostome, it lives on the 
bottom, rarely coming to the surface. For the genus Dodecabostricha 
Professor Agassiz established a new family, the Brandtide, and placed it 
in the vicinity of the Charibdeidee. While it undoubtedly has a general 
resemblance to the Charibdeide, the structure of the genital pouches 
and of the lobes of the actinostome shows that it is intermediate between 
the Aureliz and the Rhizostomz proper, combining at the same time 
structural features only found in the Pelagia. It is not known where 
Mertens found the species which is figured in Brandt’s memoir. As 
we trawled mainly on mud or clay bottoms, but few Hydroids were col- 
lected. 

All along the course of the stream we found large quantities of Tri- 
chodesmium erythreum. On one occasion, north of Hatteras, we passed 
through an extensive patch of this pelagic Alga, which colored the 
surface of the sea a dirty yellow for a distance of about a quarter of a 
mile by a hundred yards in width. 

Among the corals a fine species of Flabellum, probably the Flabellum 
alabastrum, Mos., and a few species characteristic of the West India seas 
and of the Gulf of Mexico were found to extend as far north as Cape 
Hatteras. There were a number of Pennatulee and Virgularie collected, 
probably the same species already described by Professor Verrill from the 
collections made by the United States Fish Commission, as well as a few 
Gorgoniz, among which I may mention numerous specimens of Kera- 
toisis. The Pennatulz and Gorgonie were all remarkable for their bril- 
liant bluish phosphorescence, a single Pennatula lighting up a large tub 
of water. A couple of species of Zoanthus were found in deep water. 
Among the Actiniz large specimens of Bunodes and of Edwardsia came 
up from depths of from 600 to 800 fathoms. 

Among the Echinoderms all the way from Cape Hatteras to the ex- 
tremity of George’s Shoal, Ophiomusium Lymani were quite common 
in deep water. Kchinus norvegicus is abundant, and Schizaster fragi- 
lis extends from deep water inside the 100-fathom line. A species of 
Asthenosoma and one of Phormosoma were also found in deep water, 
having the same general distribution as Ophiomusium. A fine species 


150 BULLETIN OF THE 


of Urechinus closely allied to Urechinus naresianus, and several of the 
rarer species of Starfishes, — Archaster, Porcellanaster, Luidia, Astro- 
gonium, Porania, Pteraster, and Hippasteria, — were found to extend 
far into deep water; and beyond 1,000 fathoms, off George’s Bank, 
we found several fine specimens of Brisinga, as well as three or four 
species of the remarkable deep-sea Holothurians belonging to the or- 
der of Elasmopoda; among the Crinoids, Comatula Sarsii? and a few 


specimens of Rhizocrinus. Although the line to the eastward of Charles- 
ton, S. C., was commenced off the very home of the Scutelle and other 
Clypeastroids, it is remarkable that not a single Mellita or Clypeaster 
was dredged up, either on that line or the line run in the axis of the 
Gulf Stream as far as Cape Hatteras. Hchinarachnius off George’s Shoal 
was found to extend to a much greater depth, living specimens having 
come up in the trawl from a depth of 524 fathoms. 

But few Annelids were collected, a few specimens of Nemerteans, and 
of Calymne; one of the large Eunicide, the tubes of which, sometimes 
fully fifteen inches in length, often filled the bottom of the trawl when 
dragging on muddy bottoms, was specially numerous. 

A number of species of Cephalopods, mainly Northern species already 
found in shallower waters by the United States Fish Commission, were 
brought up, many of them from considerable depths. The Gasteropods 
and Acephala were represented by many of the species collected by the 
“Lightning” and ‘‘ Porcupine,” and by the United States Fish Com- 
mission. 

Among the Crustacea the most characteristic types were the gigantic 
Pygnogonidze, a species of Willemoesia, a couple of species of Gnatho- 
phausiz, Scalpellum, and large Amphipods. 

Among the Fishes a large collection was made, mainly of Macrouride, 
including a few new genera, which will be described by Mr. Goode, of the 
United States Fish Commission. We found cod, extending to a depth 
of over 300 fathoms (off George’s Shoal). Myxine and Lophius were 
brought up from 360 fathoms, as well as Sebastes norvegicus. A species 
of Phycis, from a depth of 233 fathoms, was found to be electric, giving 
quite a strong shock to Commander Bartlett and myself. It is a small 
species, about nine inches in length, of a light ashy violet color, with dull 
yellowish spots along the sides. 

The absence of siliceous and other sponges in the collections made 
during this summer is very striking, and although the number of speci- 
mens of certain species was often very great, yet the continental faunz 
of the northern part of the east coast of the United States is poor when 


MUSEUM OF COMPARATIVE ZOOLOGY. 151 


compared to the wealth of species found in the Caribbean Sea and Gulf 
of Mexico during the former cruises of the ‘ Blake.” 

Commander Bartlett did everything in his power to make up for the 
absence of my assistant, and I was fortunate in again finding on board 
the older officers of the “ Blake,” Messrs. Sharrer, Jacoby, Peters, and 
Reynolds, whose industry, energy, and interest in the work has never 
flagged, and who have now attained a proficiency in deep-sea dredging 
hardly deemed possible three years ago. Lieut. Mentz and Dr. Persons 
joined the “Blake” during the winter of 1879, and Mr. Duvillard was 
attached to the “ Blake” as recorder during the first part of our cruise. 
During this short cruise we made no less than fifty hauls: we accom- 
plished nearly as much as during the three months of the first cruise in 
the Gulf of Mexico. 

As the greater part of the collections made during this cruise of the 
‘‘Blake” cover the extension into deep water of the ground already in 
part occupied by the United States Fish Commission, I have arranged 
with Professor Baird to send the bulk of the collections made north of 
Cape Hatteras, for final study, to some of the naturalists to whom the 
collections of the Fish Commission have been intrusted. 

During the winter of 1879-80, Commander Bartlett, while sounding 
in the Western Caribbean Sea, made some twenty hauls with the trawl, 
dredge, and tangles. These collections, made incidentally by the officers 
of the “Blake,” show the extension of the continental fauna of the 
Eastern Caribbean to its extreme western portion. Pentacrinus was 
found off Santiago de Cuba, and off Kingston, Jamaica. The deep-water 
fauna was found to be the same as the deep-water fauna of the Eastern 
Caribbean. . 

Mr. Bartlett showed that a strong current passing over a ridge, as in 
the case of the Windward Passage between Cuba and San Domingo, 
swept it entirely clean, so that but little animal life was found to live 
upon it. But immediately beyond this, on the Caribbean side, the 
mud and silt are deposited in great quantities and animal life becomes 
plenty again. This, as I have stated above, was also our experience 
during the present cruise of the “Blake,” while dredging along the so- 
called axis of the Gulf Stream. 

Lieut.-Commander C. D. Sigsbee accompanied us on the “ Blake,” to 
superintend in person the first trial of his collecting cylinder. It was 
sent down in 30 fathoms, from 5 to 25 fathoms, with quite a fresh breeze 
blowing, at about eleven in the morning, in full sunlight,—a time 
when, with a smooth sea, the pelagic animals would all have been found 


152 BULLETIN OF THE 


on the surface. The cylinder was found to work most satisfactorily, and 
brought up a few Calani, Hydroid Meduse, such as usually occur at 
the surface. A few slight modifications were suggested by Mr. Sigsbee, 
and Commander Bartlett recommended the addition of a wire-gauze trap, 
to facilitate the washing out of the microscopic animals which might be 
collected. we 
On the Ist of July the Sigsbee cylinder was tried for the second 
time in Lat. 39° 59’ 16” N., Lon. 70° 18’ 30” W., in 260 fathoms of 
water. The surface was carefully explored with the tow-net, to see what 
pelagic animals and others might be found on the surface. There were 
found Calanus, Sagitta, Annelid larvee, Hydroid Medusz, Squille em- 
bryos, Salpz, and a few Radiolarians. The cylinder, filled with water 
-which had: been carefully sifted through fine muslin, was then attached 
to the dredging wire, and lowered, so as to collect the animals to be found 
between 5 and 50 fathoms. The time occupied by the cylinder in passing 
through that space was 28 seconds. The cylinder was then brought up, 
and the sieves and gauze trap carefully washed with water, which had also 
previously been strained through fine muslin. The water was carefully 
examined, and we found the very same things which had a short time be- 
fore been collected at the surface with the tow-net and the scoop-net: 
nothing different was collected by the cylinder. The Radiolarians (two 
genera) were perhaps more numerous than at the surface. <A slight breeze 
having sprung up after the surface collections had been examined, the 
cylinder was then sent down a second time at this same station, so adjust- 
ed as to collect any animal life to be found from a depth of 50 to 100 
fathoms. Not only in this experiment, but in all the subsequent ones, 
the same precautions were taken in regard to straining the water which 
filled the cylinder at the start, as well as that used for washing out 
the sieve and the gauze trap. The messenger sent down to detach and 
open the machine occupied 21 seconds in reaching the (50 fathoms) point 
to which the cylinder was attached, and the cylinder then occupied 30 
seconds in passing to the stop at 100 fathoms. On examining the sieves, 
it was found that the more common surface things, Calanus, Sagitta, An- 
nelid larvee, Hydroid Medusze, and Squillee embryos, were entirely want- 
ing, and there were only two Radiolarians of the same species as those 
from the upper levels found after a careful scrutiny of the water. Noth- 
ing additional was brought up. The cylinder was then sent down a third 
time, lowered to a depth of 100 fathoms, the messenger sent down to 
open it (time occupied 45”), and the cylinder travelled from 100 to 
150 fathoms (time 45”), so as to collect the animal life to be obtained 


MUSEUM OF COMPARATIVE ZOOLOGY. 153 


between these limits. On drawing up the cylinder and washing out the 
sieve of the trap, not only did we find that the water contained nothing 
different from what had been brought up by the cylinder from the 
lesser depth, but it did not contain even a single Radiolarian. 

On the 15th of July, in Lat. 34° 28’ 25” N., Lon. 75° 22/ 50” W., 
we tried the Sigsbee cylinder for a third time, in a depth of 1,632 
fathoms. With the same precautions before and after using it, the cylin- 
der was sent to collect first between 5 and, 50 fathoms (time 30”). The 
surface was somewhat ruffled, and but little was found on the surface 
beyond a few Crustacean larvee and Heteropods. The cylinder con- 
tained Hydroids, fragments of Siphonophores, pelagic Algee, Crustacean 
larve, and Heteropod eggs; forms which differed from these scooped 
at the surface, but were identical with the species found on previous 
days at the surface under more favorable surface conditions of the sea. 
Next, the cylinder was arranged to collect between 50 and 100 fathoms 
(time of messenger 21” from surface to 50 fathoms, time of cylinder 
40’ to stopper from 50 to 100 fathoms). The water was found to con- 
tain only a couple of Squillez larvze, similar to those fished up at the 
surface. The third time the cylinder went down at this station it was 
lowered to collect from 100 to 150 fathoms (time of messenger from 
surface to 100 fathoms 45”, time of cylinder in passing from 100 
to 150 fathoms 45”). The water when examined contained nothing. 
No Radiolarians were found at this station, either at the surface or at 
any depth to which the cylinder was sent (150 fathoms). 

The above experiments appear to prove conclusively that the surface 
fauna of the sea is really limited to a comparatively narrow belt in 
depth, and that there is no intermediate belt, so to speak, of animal 
life, between those living on the bottom, or close to it, and the surface 
pelagic fauna. 

The experiments of using the tow-net at great depths (of 500 and 
1,000 fathoms), as was done by Mr. Murray on the “ Challenger,” were 
not conclusive, as I have already pointed out on a former occasion, while 
the so-called deep-sea Siphonophore, taken from the sounding line by 
Dr. Studer on the “Gazelle,” may have come, as I have so often observed 
in the Caribbean, from any depth. I do not mean, of course, to deny 
that there are deep-sea Meduse. The habit common to so many of our 
Acalephs (Tima, Auquorea, Ptychogena, etc.) of swimming near the bot- 
tom is well known ; Dactylometra moves near the bottom, and Polyclonia 
remains during the day turned up with the disk downwards on the mud 
bottom. I only wish to call attention to the uncertain methods adopted 
for ascertaining at what depth they live. 


154 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. 


As far as the pelagic fauna is concerned, those who have been in the 
habit of collecting surface animals know full well that the least ripple 
will send them below the reach of commotion; Miiller and Baur were 
the first to adopt the use of a tow-net sunk below the surface to col- 
lect pelagic animals when the water was disturbed. It seems natural 
to presume, as we have found from our experiments with the Sigsbee 
cylinder, that this surface fauna only sinks out of reach of the disturb- 
ances of the top, and does not extend downward to any great depth. 
The dependence of all the pelagic forms upon food which is most abun- 
dant at the surface, or near it, would naturally keep them where they 
found it in greatest quantity. 

Of course, with the death and decomposition of the pelagic forms, 
they sink to the bottom fast enough to form an important part of the 
food supply of the deep-sea animals, as can easily be ascertained by ex- 
amining the intestines of the deep-water Echinoderms. The variety 
and abundance of the pelagic fauna, and its importance as food for ma- 
rine animals, are as yet hardly realized. 

One must have sailed through miles of Salpz with the associated 
Crustacean, Annelid, and Mollusk larvee, the Acalephs, especially the 
oceanic Siphonophores, the Pteropods and Heteropods, with the Radio- 
larians, Globigerinze, and Algze, to form some idea how rich a field still 
remains to be explored. The variety of the pelagic fauna in the course 
of the Gulf Stream is probably not surpassed by that of any other part 
of the ocean. 


Newport, R. I., August 20, 1880. 


No. 9. — Reports of the Results of Dredging, under the Supervision of 
ALEXANDER AGASSIZ, on the Hast Coast of the United States, by 
the U. S. Coast Survey Steamer “ Blake,’ Commander J. R. BART- 
LETT, U.S. NV. 


VIL. 


Description of a Gravitating Trap for obtaining Specimens of Animal Life 
From Intermedial Ocean-Depths. By Linut.-COMMANDER C. D. SIGSBEE, 
On. 1. 


TuE old practice of dragging for animal forms at intermedial depths 
by means of a tow-net, which, during the several operations of lowering, 
dragging, and hauling back remained open, was not regarded by Pro- 
fessor Alexander Agassiz as affording acceptable evidence of the habitat 
of such specimens as were obtained, and he frequently referred to the 
subject during our association on board the “ Blake” in 1878. 

In March, 1880, it having been arranged that Professor Agassiz should 
make another cruise on board the “ Blake,” Commander J. R. Bartlett, 
U.S. N., commanding, he asked my co-operation in devising an apparatus 
to meet the rigid demands of the work in question. This resulted in 
the apparatus described herein, which is presented in the precise form 
used with success by the “ Blake,” although, as may readily be seen, it 
is open to great improvement, especially in minor details. 

The “Challenger” had examined intermediate depths by means of tow- 
nets trailing from the dredge-rope while hauling the dredge or trawl. 
In such a practice it must have been that the depths to which the nets 
were sunk depended in some degree on the amount of slack rope payed 
out, and also on the strain upon the dredge-rope due to the resistance en- 
countered by the dredge when dragging ; it cannot therefore be said that 
strictly determinate depths were examined by that method, even assum- 
ing that the nets gathered nothing while being lowered and hauled back. 

It occurred to me that by using an apparatus in connection with a 
line and lead, payed out vertically as in sounding, and by dragging ver- 
tically, instead of horizontally as formerly, there would be at least as 
much certainty with regard to depths as in the old method, and that 
simple mechanical devices could be invented to satisfy the conditions of 

VOL. VI. —NO. 9. 


156 BULLETIN OF THE 


the work. The scheme has been stated in my volume on “ Deep-Sea 
Sounding and Dredging,” (p. 145, foot-note,) as follows :— 

“Our plan is to trap the spécimens by giving to a cylinder, covered 
with gauze at the upper end and having a flap valve at the lower end, 
a rapid vertical descent between any two depths, as may be desired ; 
the valve during such descent to keep open, but to remain closed dur- 
ing the processes of lowering and hauling back with the rope. An idea 
of what it is intended to effect may be stated briefly thus :— Specimens 
are to be obtained between the intermediate depths a@ and b. The for- 
mer being the uppermost. With the apparatus in position, there is at a 
the cylinder suspended from a friction clamp in such a way that the 
weight of the cylinder and its frame keeps the valve closed ; at b there 
is a friction buffer. Everything being ready, a small weight or messenger 
is sent down, which on striking the clamp disengages the latter and also 
the cylinder, when messenger, clamp, and cylinder descend by their own 
weight to 6, with the valve open during the passage. When the cylinder- 
frame strikes the buffer at b, the valve is thereupon Closed, and it is kept 
closed thereafter by the weight of the messenger, clamp, and cylinder. 
The friction buffer, which is four inches long, may be regulated on board 
to give as many feet of cushioning as desired.” 

The following detailed description refers to the accompanying plate. 

The copper cylinder A, riveted to the wrought-iron frame B, has a 
flap or clapper valve, C, opening inwards and fastened to the inner arms 
of the lever D D, the latter pivoting at E. The upper end of the cylin- 
der is covered with the removable wire sieve F (60 wires to the inch), 
and inside the cylinder are the wire sieve G (27 wires to the inch) and 
the wire funnel or trap H (27 wires to the inch). 

The steel wire rope on which the cylinder travels is placed in the 
loops IJ, at the upper and lower extremities of the frame, and is re- 
tained therein by the screw-bolts J J. 

The friction clamp is composed of the frame K, the two sliding chocks 
L and M, the adjusting screw N, the guide screws O O, and the eccen- 
tric tumbler P. 

The friction buffer is composed of the frame Q, the two sliding chocks 
R and S, the adjusting screw T, the steel compression spring U, work- 
ing in a chamber, and the regulating screw V. The bearing faces of the 
two sliding chocks are corrugated, and the inward movement of each 
chock is limited by a stud forming part of the frame and fitting loosely 
within a slot in the chock. In clamping the buffer to the rope, the 
chock R is always screwed in until stopped by its stud; the steel rope 


MUSEUM OF COMPARATIVE ZOOLOGY. 15% 


is therefore always pressed between the two chocks by the elastic force 
of the spring, which may be regulated as desired. To regulate the buf- 
fer for any definite frictional resistance, clamp it to the rope, and move 
the regulating screw V well inwards; then suspend from the buffer a 
weight equal to the resistance decided upon. Move the regulating screw 
outwards until the buffer slides down the rope under the influence of 
the suspended weight. Since the chock R is always screwed ‘“ home” 
in clamping to the rope, the buffer remains regulated for prolonged use 
with the same resistance ; and, if the latter prove satisfactory, it is 
probable that the regulating screw need not be touched again for a 
whole cruise, if the buffer be rinsed in lye-water each time after use. 

A crank or key, W, is fitted to the squared heads of the regulating 
and adjusting screws, on which it locks with a spring snap, the latter 
being operated by the bent arm at one end of the crank. The stud at 
the other end of the crank is for adjusting the screws J J. 

The cast-iron messenger, X, is in two parts, connecting with each other 
by a dovetail, — or something of similar purpose. 

Professor Agassiz and Commander Bartlett added the funnel-shaped 
trap, and also the leather cushion, Y, around the valve seat, after a pre- 
liminary trial with the apparatus. 


Working the Apparatus. 


It is necessary to first regulate the buffer to cushion the stoppage of 
the falling weights, which are, cylinder and frame 38 lbs., clamp 4 lbs., 
messenger 8 lbs., total 50lbs. The ‘‘ Blake” adopted a resistance of 
about 80 lbs. (this resistance being, of course, constant during the whole 
raovement of the buffer), it having been found that a blow of that force 
resulted in no injury to the apparatus. 

On the ascent the buffer must withstand, not only the weight of the 
fifty pounds of metal, but also the resistance which the water offers to 
the passage through it of the several parts of the apparatus., Moreover, 
when the cylinder emerges from the water, it is full of that liquid, and 
with this increased weight would overcome the stated resistance of the 
buffer, and force the latter downwards until the lead was reached. To 
meet these conditions it was not thought advisable to increase the re- 
sistance of the buffer, which would involve a heavier blow against the 
apparatus, but a rope-yarn seizing or stop was placed on the rope about 
fifteen or twenty feet below the buffer, beyond which the latter could 
not pass. . 

Having secured the buffer to the rope about five or six fathoms above 


158 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. 


the lead (a very heavy lead to keep the steel rope straight) and payed 
out the length of rope required to span the stratum to be explored by the 
cylinder, the clamp and cylinder are attached, the latter being suspended 
from the former as follows. The rope having been placed between the 
two sliding chocks of the clamp, the arm of the eccentric tumbler is 
thrown up, which moves the chock M inwards ; then, by means of the 
adjusting screw, the chock L is pressed against the rope, securing the 
clamp in position. The cylinder hangs four or five inches below the 
clamp and is supported by a loop of soft wire which rests on the lip of 
the tumbler; the ends of the wire, being rove through holes in the upper 
part of the frame of the cylinder, are fastened permanently to the outer 
arms of the lever to which the valve is screwed. It is seen that by this 
method of suspension the weight of the cylinder and its frame is used to 
keep the valve closed while paying out.* The cylinder should be filled 
with water, poured down through the upper sieve, to maintain the valve 
on its seat while the cylinder is being immersed. Rope is then payed 
out slowly until the cylinder is at the desired depth, when the rope is 
stoppered, and the messenger sent down. 

The messenger strikes the arm of the eccentric tumbler, throwing it 
down and tripping the cylinder. The tumbler in falling relieves the 
pressure on the sliding chock M, which is then free to recede from the 
rope. Messenger, clamp, and cylinder fall together, the valve being held 
open by the resistance of the water. A current is established through 
the cylinder, and specimens which enter are retained by the upper sieve. 
When the buffer is reached, the valve is closed by the pressure against 
the outer arms of the lever. 

A very slight pressure on the adjusting screw of the clamp, after the 
chocks are bearing against the rope, is enough to prevent the clamp 
from slipping, but by an increased pressure on the screw a greater force 
is required to trip the tumbler, and by this feature the arm of the tum- 
bler is utilized to break the force of the blow which the body of the 
clamp receives from the falling messenger. A few rings of sheet-lead 
may be laid on top of the clamp and the buffer respectively. 


Wasuineton, D. C., September, 1880. 


*It is suggested that, in lieu of the soft wire sling, the friction clamp be constructed 
to receive the end of a stiff wire rod, proceeding from the ends of the lever D D, and 
that it be done in such a way that, when the valve is closed and the rod connected 
with the clamp, the bottom of the latter will be in firm contact with the upper part of 
the cylinder frame. Such an arrangement would effectually guard against the open- 
ing of the valve with any rapidity of descent. 


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Invented by E. D. Stgshee Liest. Cormdr: GSN, 


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by AlexanclerAgass tz und Comdr AR Bartlett SN. 


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